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eeepc Bluetooth and USB mods

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Published: Sunday, 02 March 2008 11:36

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I'm not going to take any credit for the technical details of these mods as all the information has been gleaned from the eeeUser forums (links are at the bottom of this article). This page documents my own experience of adding internal Bluetooth and an extra USB port on a UK model 4G eeePC. For those who don't want to open their new toy, check out my review of the Trust BT-2400p ultra small Bluetooth adaptor.

It is possible to fit an extra two USB ports inside the eeePC by utilising signals present on the two mini PCI-e connectors on the motherboard. In the case of my 4G model, one mini PCI-e slot is not fitted (only the solder points are present), while the other mini PCI-e slot has the wireless card fitted. The wireless card only uses the PCI-e bus for communication so the USB points present on this slot can be used without affecting the operation of WiFi.

If you are considering this mod and your eeePC does have the second mini PCI-e slot fitted, you can still proceed however be aware that any card you subsequently fit may require use of the USB data lines thus making them unavailable for use with this mod.

I'm not going to wire out two USB sockets into the expansion bay as other modders have done, instead I'm going to fit just one socket into the bay and hard wire the second port directly into a Bluetooth module which I will locate in the screen surround. This leaves more space in my expansion bay for a larger USB device to be fitted and should improve the reception on my Bluetooth card as that will be located away from the motherboard and shielding.

I'm using a surface mount soldering station to do this work and I recommend anyone undertaking such an operation uses suitable equipment. If the end of your soldering iron looks more like a builders chisel then don't attempt this procedure. It is soooo easy to end up shorting out these tiny surface mount points with a solder splash or damaging a component by overheating it.

Starting with the Bluetooth mod first then. If you're thinking of doing something like this, ensure your Bluetooth adaptor is compatible with your operating system first. So long as your adaptor is HCI compliant it should work (I guess). You can check this by plugging the adaptor into an external USB port and then by running the following commands.

Log in as superuser and download the Bluetooth utilities package:sudo suapt-get install bluez-utils

Once installation is complete, insert the the Bluetooth adaptor into a USB port and start it:hciconfig hci0 up

Check that your Bluetooth adaptor is listed as an available device:hcitool dev

If you have discoverable devices in range, run a scan and confirm they are listed:hcitool scan

If your adaptor doesn't show up as an available device or your scan results in no discoverable devices being found then you may need to source a different Bluetooth chipset. You should certainly investigate further before reaching for the screwdrivers and soldering iron!

I picked up a Newlink USB adaptor pretty cheaply. You can get some really tiny Bluetooth modules these days however this was more of the traditional 'flash-drive' size. I notice the manufacture date on the PCB is the last week of 2005 so I guess my supplier has had this sitting in stock for a while. The picture below shows the adaptor with the top of it's casing removed.

The picture below was taken after disassembling the eeePC and removing the motherboard.

The above picture shows the underside of the motherboard and all of the soldering work is going to take place in the upper left quarter. As you can see, the Bluetooth module is a fair old size in comparison with the rest of the eeePC electronics and we're going to need to shrink it down somewhat to fit it into the screen casing. This means removing it from the rest of it's case and removing the male USB connector so that all we have is the board itself. This part of the procedure will vary depending on what make or model of Bluetooth dongle you purchase. In my case, the board was easily removed from the case although the USB plug took a while to desolder. A USB plug has four connections, +5V Data- Data+ and 0V (GND). These connections are shown in the picture below for a Type A and Type B connector. With the USB plug removed, four wires were soldered directly into its place.

[see footnote for image credit]

The other end of the Bluetooth cable was connected to the mini PCI-e slot used by the wireless card and involved soldering the wires directly onto the solder points used by the connector itself. The pin outs of this slot as they appear on the board are shown in the table below, the orientation of which has been set to match the following pictures.

I used a piece of ribbon cable to attach to the Bluetooth board. This stuff is flat and flexible making it ideal to run through the narrow screen casing and hinge. The other end of the cable terminates onto available power points and onto pins 38 and 36 of the mini-PCI-e slot used by the WiFi card. There are two 5V points and you can solder your wires onto whichever you find easiest.

The picture below shows the Bluetooth board attached on the flying ribbon lead.

Upon reassembly of the case, the Bluetooth board was fitted into the left side of the screen surround. A hot-melt glue gun was used to hold the board in place.

The ribbon cable runs downwards through the hinge and into the lower casing following the same path as the left speaker and webcam wiring. The top leftmost component on the Bluetooth board is a tiny green LED which flashes when the board is powered and is continuously on when Bluetooth is active. This LED can (just about) be seen shining through the white screen casing once it's all reassembled so I can see when my Bluetooth is in operation. The picture below shows the board and the path the grey ribbon cable takes to run through the hinge and across to the underside of the motherboard.

I mentioned the hciconfig hci0 up command earlier which is used for activating the adaptor and I should point out that the adaptor can be deactivated with hciconfig hci0 down

The second half of this mod is to equip the expansion bay with a USB socket which will allow for insertion of other USB devices within the casing of the eeePC. This is pretty much the same as the Bluetooth mod except the connections are made to the second mini PCI-e slot and the cable will terminate on a USB socket instead of being hard wired into a dedicated board.

I was going to use the socket off a USB extension lead (pictured below), however this moulded socket is quite large and would be inconvenient to fit. Instead, I nabbed a PCB mounted socket off a dead laptop motherboard that was in the scrap box.

Connection to the second mini PCI-e socket is the same as before except the solder points have been rotated 90 degrees anti-clockwise. 5V and 0V points remain the same. Again, ribbon cable has been used and the connections are made directly to the socket.

A hot melt glue gun was used to attach the socket to the motherboard. Glue was also applied to all the connections between the ribbon cable and motherboard to act as strain relief and minimise the chances of a wire breaking off and shorting out on nearby points.

Below: a close up of the socket glued to the board. Glue is also applied to the solder points on the socket to help with strain relief and insulate the points from the metal shielding of the case after reassembly.

After reassembly the new USB socket is available in the expansion bay. It's location on the board is such that it butts up against the internal fan so a USB device can be inserted with the confidence of knowing the glue holding the socket in place won't break and push the socket further into the case. Some care must be taken removing a device however but by the nature of the location of this socket, devices are generally meant to be inserted and left in place, after all, there are three USB ports available externally for hot plugging hardware.

The picture below shows a flash drive inserted into the expansion bay port. This particular flash drive is quite large but still fits. As with the Bluetooth dongle though, plastic cases can be dismantled if necessary to shrink down the overall size while still allowing a board to be directly fitted into the socket.

For further information and pictures taken by other modders, check out the following links: